diff --git a/plone/app/discussion/browser/comments.py b/plone/app/discussion/browser/comments.py
index 387cead..2056aa2 100644
--- a/plone/app/discussion/browser/comments.py
+++ b/plone/app/discussion/browser/comments.py
@@ -2,6 +2,7 @@ from AccessControl import getSecurityManager
 from AccessControl import Unauthorized
 from Acquisition import aq_inner
 from datetime import datetime
+from datetime import timezone
 from DateTime import DateTime
 from plone.app.discussion import _
 from plone.app.discussion.browser.validator import CaptchaValidator
@@ -192,8 +193,8 @@ class CommentForm(extensible.ExtensibleForm, form.Form):
             setattr(comment, attribute, data[attribute])
 
         # Set dates
-        comment.creation_date = datetime.utcnow()
-        comment.modification_date = datetime.utcnow()
+        comment.creation_date = datetime.now(timezone.utc)
+        comment.modification_date = datetime.now(timezone.utc)
 
         # Get author name and email
         comment.author_name, comment.author_email = self.get_author(data)
diff --git a/plone/app/discussion/comment.py b/plone/app/discussion/comment.py
index 438e726..8e9be09 100644
--- a/plone/app/discussion/comment.py
+++ b/plone/app/discussion/comment.py
@@ -6,6 +6,7 @@ from Acquisition import aq_base
 from Acquisition import aq_parent
 from Acquisition import Implicit
 from datetime import datetime
+from datetime import timezone
 from OFS.owner import Owned
 from OFS.role import RoleManager
 from OFS.Traversable import Traversable
@@ -119,7 +120,7 @@ class Comment(
     # IConversation.addComment().
 
     def __init__(self):
-        self.creation_date = self.modification_date = datetime.utcnow()
+        self.creation_date = self.modification_date = datetime.now(timezone.utc)
         self.mime_type = "text/plain"
 
         user = getSecurityManager().getUser()
diff --git a/plone/app/discussion/profiles/default/metadata.xml b/plone/app/discussion/profiles/default/metadata.xml
index 141a440..3b4e730 100644
--- a/plone/app/discussion/profiles/default/metadata.xml
+++ b/plone/app/discussion/profiles/default/metadata.xml
@@ -1,5 +1,5 @@
 <metadata>
- <version>2000</version>
+ <version>2001</version>
  <dependencies>
   <dependency>profile-plone.resource:default</dependency>
   <dependency>profile-plone.app.registry:default</dependency>
diff --git a/plone/app/discussion/upgrades.py b/plone/app/discussion/upgrades.py
index 40cdc8f..fbad45c 100644
--- a/plone/app/discussion/upgrades.py
+++ b/plone/app/discussion/upgrades.py
@@ -2,6 +2,8 @@ from plone.app.discussion.interfaces import IDiscussionSettings
 from plone.registry.interfaces import IRegistry
 from Products.CMFCore.utils import getToolByName
 from zope.component import getUtility
+from plone import api
+from datetime import timezone
 
 import logging
 
@@ -77,3 +79,24 @@ def add_js_to_plone_legacy(context):
 def extend_review_workflow(context):
     """Apply changes made to review workflow."""
     upgrade_comment_workflows_retain_current_workflow(context)
+
+
+def set_timezone_on_dates(context):
+    """Ensure timezone data is stored against all creation/modified dates"""
+    pc = api.portal.get_tool('portal_catalog')
+    creations = 0
+    modifieds = 0
+    logger.info('Setting timezone information on comment dates')
+    comments = pc.search({'Type': 'Comment'})
+    for cbrain in comments:
+        comment = cbrain.getObject()
+        if not comment.creation_date.tzinfo:
+            creations += 1
+            comment.creation_date = \
+                comment.creation_date.astimezone(timezone.utc)
+        if not comment.modification_date.tzinfo:
+            modifieds += 1
+            comment.modification_date = \
+                comment.modification_date.astimezone(timezone.utc)
+    logger.info('Updated %i creation dates and %i modification dates' %
+                (creations, modifieds))
diff --git a/plone/app/discussion/upgrades.zcml b/plone/app/discussion/upgrades.zcml
index 20b288e..7f8ffe7 100644
--- a/plone/app/discussion/upgrades.zcml
+++ b/plone/app/discussion/upgrades.zcml
@@ -88,4 +88,15 @@
         handler=".upgrades.upgrade_comment_workflows" />
   </genericsetup:upgradeSteps>
 
+  <genericsetup:upgradeSteps
+    source="2000"
+    destination="2001"
+    profile="plone.app.discussion:default">
+    <genericsetup:upgradeStep
+        title="Set timezone on comment dates"
+        description="Ensure the timezone is set for comment dates"
+        handler=".upgrades.set_timezone_on_dates"
+        />
+  </genericsetup:upgradeSteps>
+
 </configure>